6 4 o SCIENCE PROGRESS 



probably a far grander and loftier chain — as the Nagelfluh 

 and the Molasse of Switzerland are of the Alps." 



Five years later in a thesis on The Geology of the North-east 

 of Caithness, after describing the Old and New Red Sandstones 

 as " the monuments of two great continental periods which 

 prevailed over wide areas in the northern hemisphere," I 

 observed (note, p. 46) : " It seems probable that some of 

 the widespread conglomerates of Caithness and the Moray 

 Firth may have been deposited sub-aerially by mountain 

 torrents (intermittently swollen by heavy rains) as they 

 reached lower and less hilly regions." . . . After referring 

 to Prof. Bonney's address, I continued : " The intercalated 

 fish-bearing beds in the Moray Firth would represent a short 

 period during which lacustrine conditions occurred. Of course 

 the sub-aerial deposits need not have been contemporaneous 

 in different places ; in Caithness they probably represent 

 a period when more continental conditions prevailed than 

 during the deposition of the Caithness flags " ; and the sug- 

 gestion was made that " lakes and streams afford a greater 

 variety of environment than the sea — a variety that is prob- 

 ably an important element among the conditions favourable 

 for rapid evolutionary change." I subsequently emphasised 

 the torrential character of many of the Old Red Sandstone 

 deposits in a contribution to the Handbuch der regionalen 

 Geologie which was in the press at the time of the outbreak of 

 the war. It may be added that Walther early took a similar 

 view of the origin of the Old Red Sandstone. 



J. W. Evans. 



[I am much obliged for Dr. Evans's gentle reminder that the 

 theory of the fluviatile origin of the Old Red Sandstone dates 

 back at least as far as Prof. Bonney's Presidential Address of 

 1886 and Dr. Evans's own work of 1891, and I much regret 

 having omitted their names from my short synopsis of the 

 history of views regarding the Old Red Sandstone. Of course 

 the essay-review was only intended to summarise for geologists 

 an interesting theory of the origin of the Old Red Sandstone, 

 developed in detail for the first time in the publications under 

 review. It was not intended to be an exhaustive account of 

 the formation, or I should have dealt with the literature in 

 much greater detail. — G. W. T.] 



